Attenuation of mirror image and enhancement of the signal-to-noise ratio in a Talbot bands optical coherence tomography system
University of Kent, School of Physical Sciences, Applied Optics Group, Gilles Lane, Canterbury, Kent CT2 7NH United Kingdom.Journal of Biomedical Optics (Impact Factor: 2.86). 07/2011; 16(7):076010. DOI: 10.1117/1.3598446
A Fourier domain optical coherence tomography setup is presented built around an optical configuration that exhibits Talbot bands. A low astigmatism spectrometer is used, employing a spherical mirror and a cylindrical lens between a diffraction grating and a linear CCD camera. To produce Talbot bands, the two interferometer beams--object and reference--are laterally shifted in respect to each other in their way toward the diffraction grating. This allows attenuation of mirror terms and optimization of the sensitivity profile. We evaluate the optimization of the sensitivity profile with depth, in respect to its overall strength and its position peak, which can be shifted toward a larger optical path difference in the interferometer. We demonstrate the efficiency of such a configuration at large depths by imaging a thick phantom and human skin in vivo for different values of the lateral distance between the two beams.
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ABSTRACT: We present a Fourier domain optical coherence tomography set-up built around an optical configuration that exhibits Talbot bands. To produce Talbot bands, the two interferometer beams, object and reference are laterally shifted in their way towards the diffraction grating. This allows attenuation of mirror terms and optimisation of the sensitivity profile. We imaged the human skin in-vivo, and quantified the profile of the sensitivity profile in tissue by measuring the ratio between the strengths of signals originating in the reticular dermis and in the stratum corneum for different values of the lateral shift of the two interfering beams.Proceedings of SPIE - The International Society for Optical Engineering 02/2012; DOI:10.1117/12.905278 · 0.20 Impact Factor
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ABSTRACT: In this paper we show how to advantageously combine two effects to enhance the sensitivity with depth in Fourier domain (FD) optical coherence tomography (OCT): Talbot bands (TB) and Gabor-based fusion (GF) technique. TB operation is achieved by routing the two beams, from the object arm and from the reference arm in the OCT interferometer, along parallel separate paths towards the spectrometer. By adjusting the lateral gap between the two beams in their way towards the spectrometer, the position for the maximum of contrast variation of spectral modulation versus the optical path difference in the interferometer is adjusted. For five values of the focus position, the gap between the two beams is readjusted to reach maximum sensitivity. Then, similar to the procedure employed in the GF technique, a compound image is formed by stitching together the parts of the five images that exhibited maximum brightness. The smaller the diameters of the two beams, the narrower the visibility profile versus depth in Talbot bands, which brings advantages in terms of mirror terms attenuation. However, this leads to a larger spot on the linear camera, which introduces losses, therefore the combined procedure, TB/GF is investigated for four different values of the beam diameters of the two beams. Future cameras with larger pixel size may take full advantage of the TB/GF procedure proposed here.Optics Express 02/2012; 20(5):5368-83. DOI:10.1364/OE.20.005368 · 3.49 Impact Factor
Article: Optical coherence tomography[Show abstract] [Hide abstract]
ABSTRACT: The review provides a concise explanation of principles of operation of different optical coherence tomography methods. A comparative analysis of their advantages and disadvantages is presented in relation to specific applications. The review will assist the reader in making an educated choice on the most suitable optical coherence tomography method to be used in a particular application.Journal of Microscopy 06/2012; 247(3):209-19. DOI:10.1111/j.1365-2818.2012.03619.x · 2.33 Impact Factor
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